matplotlib.pyplot.barbs#
- matplotlib.pyplot.barbs(*args, data=None, **kwargs)[source]#
Plot a 2D field of barbs.
Call signature:
barbs([X, Y], U, V, [C], **kwargs)
Where X, Y define the barb locations, U, V define the barb directions, and C optionally sets the color.
All arguments may be 1D or 2D. U, V, C may be masked arrays, but masked X, Y are not supported at present.
Barbs are traditionally used in meteorology as a way to plot the speed and direction of wind observations, but can technically be used to plot any two dimensional vector quantity. As opposed to arrows, which give vector magnitude by the length of the arrow, the barbs give more quantitative information about the vector magnitude by putting slanted lines or a triangle for various increments in magnitude, as show schematically below:
: /\ \ : / \ \ : / \ \ \ : / \ \ \ : ------------------------------
The largest increment is given by a triangle (or "flag"). After those come full lines (barbs). The smallest increment is a half line. There is only, of course, ever at most 1 half line. If the magnitude is small and only needs a single half-line and no full lines or triangles, the half-line is offset from the end of the barb so that it can be easily distinguished from barbs with a single full line. The magnitude for the barb shown above would nominally be 65, using the standard increments of 50, 10, and 5.
See also https://en.wikipedia.org/wiki/Wind_barb.
- Parameters:
- X, Y1D or 2D array-like, optional
The x and y coordinates of the barb locations. See pivot for how the barbs are drawn to the x, y positions.
If not given, they will be generated as a uniform integer meshgrid based on the dimensions of U and V.
If X and Y are 1D but U, V are 2D, X, Y are expanded to 2D using
X, Y = np.meshgrid(X, Y)
. In this caselen(X)
andlen(Y)
must match the column and row dimensions of U and V.- U, V1D or 2D array-like
The x and y components of the barb shaft.
- C1D or 2D array-like, optional
Numeric data that defines the barb colors by colormapping via norm and cmap.
This does not support explicit colors. If you want to set colors directly, use barbcolor instead.
- lengthfloat, default: 7
Length of the barb in points; the other parts of the barb are scaled against this.
- pivot{'tip', 'middle'} or float, default: 'tip'
The part of the arrow that is anchored to the X, Y grid. The barb rotates about this point. This can also be a number, which shifts the start of the barb that many points away from grid point.
- barbcolorcolor or color sequence
The color of all parts of the barb except for the flags. This parameter is analogous to the edgecolor parameter for polygons, which can be used instead. However this parameter will override facecolor.
- flagcolorcolor or color sequence
The color of any flags on the barb. This parameter is analogous to the facecolor parameter for polygons, which can be used instead. However, this parameter will override facecolor. If this is not set (and C has not either) then flagcolor will be set to match barbcolor so that the barb has a uniform color. If C has been set, flagcolor has no effect.
- sizesdict, optional
A dictionary of coefficients specifying the ratio of a given feature to the length of the barb. Only those values one wishes to override need to be included. These features include:
'spacing' - space between features (flags, full/half barbs)
'height' - height (distance from shaft to top) of a flag or full barb
'width' - width of a flag, twice the width of a full barb
'emptybarb' - radius of the circle used for low magnitudes
- fill_emptybool, default: False
Whether the empty barbs (circles) that are drawn should be filled with the flag color. If they are not filled, the center is transparent.
- roundingbool, default: True
Whether the vector magnitude should be rounded when allocating barb components. If True, the magnitude is rounded to the nearest multiple of the half-barb increment. If False, the magnitude is simply truncated to the next lowest multiple.
- barb_incrementsdict, optional
A dictionary of increments specifying values to associate with different parts of the barb. Only those values one wishes to override need to be included.
'half' - half barbs (Default is 5)
'full' - full barbs (Default is 10)
'flag' - flags (default is 50)
- flip_barbbool or array-like of bool, default: False
Whether the lines and flags should point opposite to normal. Normal behavior is for the barbs and lines to point right (comes from wind barbs having these features point towards low pressure in the Northern Hemisphere).
A single value is applied to all barbs. Individual barbs can be flipped by passing a bool array of the same size as U and V.
- Returns:
- barbs
Barbs
- barbs
- Other Parameters:
- dataindexable object, optional
If given, all parameters also accept a string
s
, which is interpreted asdata[s]
(unless this raises an exception).- **kwargs
The barbs can further be customized using
PolyCollection
keyword arguments:Property
Description
a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array and two offsets from the bottom left corner of the image
array-like or scalar or None
bool
antialiased
or aa or antialiasedsbool or list of bools
array-like or None
CapStyle
or {'butt', 'projecting', 'round'}(vmin: float, vmax: float)
bool
Patch or (Path, Transform) or None
Colormap
or str or Nonecolor or list of RGBA tuples
edgecolor
or ec or edgecolorscolor or list of colors or 'face'
facecolor
or facecolors or fccolor or list of colors
str
{'/', '\', '|', '-', '+', 'x', 'o', 'O', '.', '*'}
bool
JoinStyle
or {'miter', 'round', 'bevel'}object
linestyle
or dashes or linestyles or lsstr or tuple or list thereof
linewidth
or linewidths or lwfloat or list of floats
bool
Normalize
or str or Noneoffset_transform
or transOffsetunknown
(N, 2) or (2,) array-like
list of array-like
None or bool or float or callable
unknown
bool
sizes
numpy.ndarray
or None(scale: float, length: float, randomness: float)
bool or None
str
list of str or None
list of array-like
unknown
bool
float